1. Field of the Invention
This invention pertains to the field of electronic communication. More particularly, the invention pertains to fixed line electrical communication systems. In greater particularity, the invention relates to pulse data transmission over long line lengths. By way of further characterization, but without limitation thereto, the invention will be described as it pertains to a two-line, pulse-data transfer system between a plurality of spaced terminals.
2. Description of Prior Art
Prior art fixed line systems suffer from engineering trade-offs to establish a threshold sensitive enough to enable reception from distant transmission terminals but capable of excluding noise in the presence of strong signals. That is, if the thresholding circuitry will permit detection of weak signals originating at remote terminals, it will be ineffective to reduce noise in the presence of strong signals. Such trade-offs have limited the maximum length of data transfer lines.
Prior art systems now in use also suffer from interruption of communication ability when a catastrophic failure of the transmission line occurs. That is, signal reflections from shorted or open lines produce spurious signals. This limitation has limited installation in large naval vessels where combat conditions increase the likelihood of this type of failure.
Other shortcomings in the prior art are, of course, known and each problem has a known method of reducing the effect of the particular shortcoming. Although many of these prior art systems are satisfactory for their intended purposes, they have been unable to provide a reliable, high-speed digital communication system suitable for use in hazardous naval environments.